Cast structure for induction device



Jan 17, 1956 H. R. GOULD E AL CAST STRUCTURE FOR INDUCTION DEVICE Filed May 28, 1954 United States Patent CAST STRUCTURE FOR INDUCTION DEVICE Herbert R. Gould, Danville, Ill., and Richard L. Hamilton, Fort Wayne, Ind., assignors to General Electric Company, a corporation of New York Application May 23, 1954, Serial No. 433,108

Claims. (Cl. 336-96) This invention relates to induction devices and more particularly to induction devices encased in cast or molded material.

In the past, induction devices such as transformers, particularly the smaller categories thereof, provided with a metallic housing, usually filled with a potting compound to transfer heat from the inductive structure to the housing. Securement of the structure of the device to the housing frequently necessitated a relatively large number of separate parts which greatly increased the cost of production of the device both as to assembly and as to the cost of the parts. In addition, the housing itself had to be in at least two parts so that after insertion of the structure of the device into one part, the leads from the device could be passed through openings in the other part before the two housing parts were secured together. While it is highly important that the number of component parts and the necessary time for assembling these parts be reduced as much as possible, this reduction should be effected without decreasing in any way the efficiency or reliability of the device. It is also desirable that the device be encased in a mass of insulating material to preserve the necessary heat dissipation.

It is therefore, an object of this invention to provide an improved induction device incorporating the desirable features set forth above.

Further objects and advantages of this invention will become apparent and the invention will be better understood by reference to the following description and the accompanying drawing, and the features of novelty which characterize this invention will be pointed out with particularity in the claims annexed to and forming a part of this specification.

This invention, in its broadest aspect, includes a core with a coil positioned on a part thereof. Means for clamping the core are provided, and terminal means are secured to the clamping means. With the entire inductive structure thus assembled, an insulating material is cast about the assembly. This is preferably achieved by placing the assembly in a mold, and pouring in the insulating material so that it fills all voids in the assembly and encloses it, with the minimum exception of the ends of the terminal means.

In the drawing,

Figure 1 is a side view, partly in cross section, of the improved inductive device arranged in a mold so that a housing may be formed;

Figure 2 is an exploded view in perspective, partly broken away, of the improved structure of the invention before the housing is formed; and

Figure 3 is a view in perspective, partly broken away, of the improved structure of the invention after the housing has been formed about it.

Referrring now to the figures of the drawing, there is shown a transformer cor -generally designated as 1,' made 'up of a group of super-imposed laminations of magnetic material, such as 2. In In the instant embodiment, there is provided a core leg 3 on which a coil 4 is positioned.

2,731,607 Patented Jan. 17, 1956 Coil 4 is made up of two separate windings each having a plurality of turns of nonmagnetic electrically conductive wire, and has extending therefrom leads 5, two for each winding, which are adapted to be connected to external leads (not shown). It will be understood that the structure set forth above is for illustrative purposes, and that other inductive devices and other transformer structures may be used with equal effectiveness.

A pair of clamping plates 6 and 7 are provided; each of these plates is substantially rectangular and is provided with outstanding rounded corners 8, each of which has an opening 9 formed therein. Each of the plates 6 and 7 has an opening, such as 10, formed therein so that the plates may be placed on opposite faces of core 1 respectively so as to fit over the ends of coil 4. Once plates 6 and 7 have been so positioned, headed bolts 11 are inserted through the openings 9 of the two plates 6 and 7 in spaced parallel relation to each other so that each bolt head 39 engages the surface of member 6.

Four substantially cylindrical stud members 12 are provided respectively for the four bolts 11. Each of the stud members has an internally threaded opening 13 extending therethrough for a portion of its length, and an annular groove extending about its periphery intermediate its ends and beyond opening 13, as denoted by 14. Each of the studs 12 is threaded onto one of the bolts 11 until it securely abuts against top clamping member 7 so as to complete the clamping of the core member 1 between members 6 and 7. It will be observed that the studs 12 are used as nuts in this instance in cooperation with bolts 11. Each stud member 12 has a mounting bolt 16, which is preferably integrally secured to end 15 0f the stud member. Such a configuration of studs 12, in combination with the bolts 11 and 16, is deemed preferable in most instances because of various factors. These include the fact that the annular groove 14 in conjunction with a hole extended through that part of the stud may decrease the amount of material at that point so as to seriously weaken the stud, and the fact that the core need not al ways be a rectilinear solid and that, therefore, a single bolt extended through the stud 14 instead of the arrangement used might well result in having the ends of the bolts in dirierent planes, a feature which is generally deemed undesirable for mounting purposes. In addition, the present arrangement provides fixed mounting bolts which may be properly secured during assembly without regard to conditions affecting the positions of bolts 12. However, it will be seen that under certain conditions, a single bolt could be extended through each stud instead of the structure used and such an arrangement would, therefore, come within the scope of this invention.

A rectangular board 17, which is preferably formed of a rigid insulating material, is provided with a recess, or inversely curved portion, 18 in each of its four corners, each recess being so proportioned as to engage and fit within a groove 14 of a stud 12. Board 17 is arranged to be snapped down until each groove 18 is in position within an annular groove 14 of a stud, so that the board is held in position between the four studs. A number of openings 19 are formed in board 17, and a terminal member 20 of standard design may be fittedwithin each opening 19 and secured to board 17 by any desired method. In the instant embodiment, each terminal 20 is provided with an opening 21 extending therethrough and an annular flange 22 at one end thereof to position the terminal on the terminal board 17. Each coil lead 5 is secured to a terminal 20 in conductive relation therewith. Each terminal is formed of conductive material so that an external lead (not shown) may be secured thereto and thereby be effectively in contact with a coil lead 5.

When the transformer has been assembled with the core 1 clamped in position and the terminal board 17 secured between the studs 12, the entire structure is arranged in a mold 23 and maintained in position therein by means (not shown) which may be arranged to grasp one or more of bolts 16. Once the transformer structure is so positioned within mold 23, a casting material 25 having the desired properties of insulation, strength, and heat transfer when hardened, such as for instance, a polyester type resin (commonly called permafil), may be poured into the mold up to the level of line 24. The casting is then hardened and is removed from mold 23. Once it is removed from the mold, the transformer structure will be complete as shown in Figure 3. Casting material 25 will have hardened into a solid housing having the desired dielectric mechanical, and thermal qualities. The casting material, henceforth referred to as perrnafil, will fill all open places inthe tran former structure and will thus hold all the parts in the desired relative positions in which they have been assembled prior to the casting operation. It will be seen that terminal board 17 is entirely covered and that the terminals 20 extend out of surface 28 of the cast housing. The terminals are in the desired position in which they were placed during assembly, and will remain so in view of the fact that the housing has been cast around them. The only other portion of the transformer which may extend outside the housing will be the tops 29 of studs 12 and the mounting bolts 16.

It will now be apparent that this invention provides an inductive device in which the number of components has been reduced to the bare minimum with each component performing a certain specified function. For instance, the studs 12 serve as nuts for the core bolts 11, provide slots 14 to position the terminal board 17, afford properly positioned threaded members 16 for the mounting of the transformer, provide rigid support for the core 1 and coil 4, and supply the means by which the core 1 and coil 4 are held in position in the mold 23 during the casting operation.

While this invention has been explained by describing a particular embodiment thereof, it will be apparent that improvements and modifications may be made without departing from'the scope of the invention as defined in the appended claims.

. What we claim as new and desire to secure by Letters Patent of the United States is:

1. An inductive device comprising a laminated core; a coil positioned thereon; means for clamping said core comprisinga pair of members positioned respectively at each face of said core, a plurality of elongated members each extending through both of said pair of members and having an end projecting past one of said pair of members, and a plurality of stud members secured respectively to the projecting ends of said elongated members thereby to clamp said pair of members to said core; terminal means secured between said stud members; and a mass of insulating material arranged as a housing to enclose said core said coil and said clamping members, at least a part of said terminal means being arranged to extend outside said material.

2. An inductive device comprising a laminated core; a coil positioned thereon; means for clamping said core comprising a pair of flat members positioned respectively at each face of said core and having openings to accommodate said coil, a plurality of threaded members each extending through both of said flat members and respectively having an end projecting past one of said flat members, and a plurality of internally threaded stud members threaded respectively over the projecting ends of said elongated members against said one flat members thereby to clamp said pair of members to said core; terminal means secured between said stud members; and a mass of cast insulating material arranged as a housing to enclose said core said coil and said clamping members,

at least a part of said terminal means being arranged to extend outside said cast material.

3. An inductive device comprising a laminated core; a coil positioned thereon; means for clamping said core comprising a pair of flat members positioned respectively at each face of said core and having openings to accommodate said coil, a plurality of headed threaded members each extending through both of said flat members and having the headed end engaging one of said flat members, said threaded members being in spaced parallel relation to each other and each having an end projecting past the other of said fiat members, and a plurality of stud members threaded interrnally through a portion thereof, said stud members being threadedly arranged over the projecting ends of said elongated members re- 7 ively against the other flat member thereby to clamp said pair of members to said core, each of said stud members having an annular groove formed therearound; a terminal board arranged with its periperal portion extending into said annular grooves whereby said board is positioned by said stud members; a plurality of terminal members secured to and extending through said board; and a mass of cast insulating material arranged as a housing about said transformer, said terminal members being arranged to extend outside said cast material.

4. An inductive device comprising a laminated core; a coil positioned thereon; means for clamping said core comprising a pair of flat members positioned respectively at each face of said core, said members each having a plurality of small openings adjacent their peripheries and each having a relatively large opening to accommodate an end of said coil, a plurality of headed threaded members extending respectively through said small openings in both of said fiat members and each having the headed end engaging one of said flat members, said threaded members being in spaced parallel relation to each other and each having an end projecting past the other of said flat members, and a plurality of stud members threaded intermaliy through a portion thereof, said stud members being threadedly arranged over the projecting ends of said elongated members respectively against the other fiat member thereby to clamp said pair of members to said core, each of said stud members having an annular groove formed therearound, a terminal board arranged with its peripheral portion extending into said annular grooves whereby said board is positioned by said stud members; a plurality of terminal members secured to and extending through said board; a plurality of second threaded members integrally secured to said stud members respectively and positioned oppositely from said internally threaded portions respectively; and a mass of cast insulating material arranged as a housing about said transformer, said terminal members and said second threaded members being arranged to extend outside said cast material.

5. An inductive device comprising a laminated core, a coil positioned thereon and having a plurality of electrical leads extending therefrom; means for clamping said core comprising a pair of fiat substantially rectangular members positioned respectively at each face of said core, said members each having a plurality of small openings positioned respectively adjacent the corners thereof and each having a centrally located relatively large opening to accommodate an end of said coil, a plurality of beaded threaded members extending respectively through said small openings in both of said flat members and each having the headed end engaging one of said fiat members, said threaded members being arranged parallel to each other and each having an end projecting past the other of said flat members, and a plurality of substantially cylindrical stud. members threaded internally along a portion of the length thereof, said stud members being threadedly arranged over the projecting ends of said elongated members respectively against the other fiat member thereby to clamp said pair of members to said core, each of said stud members having an annular groove formed thereon, a plurality of threaded mounting members integrally secured to said stud members respectively, said mounting members be ing respectively coaxial With said internally threaded portions of said stud members and on the opposite sides of said grooves therefrom; a substantially rectangular terminal board of rigid insulating material having its corners inversely curved, said corners extending into said grooves respectively whereby said board is positioned by said stud members; a plurality of terminal members secured to and extending through said board, said leads being electrically and mechanically secured to said terminals respectively; and a mass of cast permafil arranged as a housing about said transformer, a portion of said terminal members said mounting members and a portion of said stud members being arranged to extend outside said cast permafil housing.

in the file of this patent UNITED STATES PATENTS 

